However, he said the decision was ultimately down to the Labour members to decide which industries to focus on.

"This is the whole point of our conference this year, we are listening to our members and saying what are your priorities" he told the Today Programme.

When asked if shareholders would get the full market value, he said that parliament would decide the price, as happened in every nationalisation in the past. He explained:

The value of any industry that is brought into public ownership is determined by parliament itself, and that will be a detailed assessment.

He also indicated that bad behaviour in the past could affect how much shareholders would receive:

The perceived behaviour affects the price. That will be determined by parliament. When parliament determines that, what those shareholders will get is a secure bond which is much more secure than what they’ve got at the moment.

During his media round this morning, McDonnell also admitted Labour's position on Brexit and the single market has not been agreed - and still might be finalised if a snap election was called in the next six months.

He told BBC Breakfast the party was not seeking to stifle views on Brexit during the conference.

“I think you’ve got this wrong,” he said. “There will be a debate about Brexit, a very thorough one. Keir Starmer will be introducing it, there will be the normal report from the national executive committee, and if people want to vote on that they can."

He insisted that Jeremy Corbyn and the rest of the leadership team had nothing to do with deciding which motions would be debated, saying: "The delegates themselves, no longer the leadership, decide on what motions they’ll debate, and that’s what the delegates have done. They’ve chosen other issues.”

During a separate interview with the Today Programme, McDonnell admitted Labour's position was still not fixed.

“We’re building that answer now, but we’ve got to have consensus,” he said. “We can’t be in a situation where we try to impose a solution on the British people.”

The party was still working on “a compromise within the community that brings us the benefits of the EU, as they are, and overcomes some of the disbenefits”.

He added: “We think we can build a compromise and consensus, The country was split down the middle – we’ve got to try and bring the country back together again.We think we’re the only party that can do that.”